package avltree;

import binarysearchtree.BST;
import map.FileOperation;

import java.util.*;

/**
 * 平衡二叉树
 * 对于任意一个节点，左子树和右子树的高度差不能超过1
 * 是二分搜索树的改良，需要满足二分搜索树的性质
 * @param <K>
 * @param <V>
 */
public class AVLTree <K extends Comparable<K>, V> {

    private class Node {
        public K key;
        public V value;
        public Node left, right;
        public int height;

        public Node(K key, V value) {
            this.key = key;
            this.value = value;
            left = null;
            right = null;
            height = 1;
        }
    }

    private Node root;
    private int size;

    public AVLTree() {
        root = null;
        size = 0;
    }

    public int size() {
        return size;
    }

    public boolean isEmpty() {
        return size == 0;
    }

    //判断该二叉树是否是一颗二分搜索树
    public boolean isBST(){
        ArrayList<K> keys = new ArrayList<>();
        inOrder(root, keys);

        for (int i = 1; i < keys.size(); i++) {
            if(keys.get(i-1).compareTo(keys.get(i)) > 0){
                return false;
            }
        }
        return true;
    }

    private void inOrder(Node node, ArrayList<K> keys) {
        if(node == null){
            return;
        }
        inOrder(node.left, keys);
        keys.add(node.key);
        inOrder(node.right, keys);


    }

    //判断该二叉树是否是一颗平衡二叉树
    public boolean isBalanced(){
        return isBalanced(root);
    }

    private boolean isBalanced(Node node) {
        if(node == null){
            return true;
        }

        int balanceFactor = getBalanceFactor(node);
        if(Math.abs(balanceFactor) > 1){
            return false;
        }

        return isBalanced(node.left) && isBalanced(node.right);
    }


    private int getHeight(Node node){
        if (node == null){
            return 0;
        }
        return node.height;
    }

    private int getBalanceFactor(Node node){
        if (node == null){
            return 0;
        }
        return getHeight(node.left) - getHeight(node.right);
    }
    // 对节点y进行向右旋转操作，返回旋转后新的根节点x
    //        y                              x
    //       / \                           /   \
    //      x   T4     向右旋转 (y)        z     y
    //     / \       - - - - - - - ->    / \   / \
    //    z   T3                       T1  T2 T3 T4
    //   / \
    // T1   T2
    private Node rightRotate(Node y){

        Node x = y.left;
        Node t3 = x.right;
        //向右旋转
        x.right = y;
        y.left = t3;
        //更新高度
        y.height = Math.max(getHeight(y.left), getHeight(y.right)) + 1;
        x.height = Math.max(getHeight(x.left), getHeight(x.right)) + 1;

        return x;
    }

    // 对节点y进行向左旋转操作，返回旋转后新的根节点x
    //    y                             x
    //  /  \                          /   \
    // T1   x      向左旋转 (y)       y     z
    //     / \   - - - - - - - ->   / \   / \
    //   T2  z                     T1 T2 T3 T4
    //      / \
    //     T3 T4
    private Node leftRotate(Node y) {
        Node x = y.right;
        Node t2 = x.left;
        //向左旋转
        x.left = y;
        y.right = t2;
        //更新高度
        y.height = Math.max(getHeight(y.left), getHeight(y.right)) + 1;
        x.height = Math.max(getHeight(x.left), getHeight(x.right)) + 1;

        return x;
    }

    public void add(K key, V value) {
        root = add(root, key, value);
    }

    //向以node为根的二分搜索树中插入元素e,递归算法
    // 返回插入新节点后二分搜索树的根
    private Node add(Node node, K key, V value) {
        if (node == null) {
            size++;
            return new Node(key, value);
        }

        if (key.compareTo(node.key) < 0) {
            node.left = add(node.left, key,value);
        } else if (key.compareTo(node.key) > 0) {
            node.right = add(node.right, key,value);
        } else {
            node.value = value;
        }

        //更新高度
        node.height = 1 + Math.max(getHeight(node.left), getHeight(node.right));

        //计算平衡因子
        int balanceFactor = getBalanceFactor(node);
        /*if (Math.abs(balanceFactor) > 1){
            System.out.println("unbalanced:" + balanceFactor);
        }*/

        //平衡维护：大于1说明是不平衡，
        // 然后根据其左子树平衡因子大于等于0，
        //整体是左边倾斜的
        // LL
        if (balanceFactor > 1 && getBalanceFactor(node.left) >= 0){
            return rightRotate(node);
        }

        //平衡维护：小于-1说明是不平衡，
        // 根据其右子树平衡因子小于等于0，
        //整体是右边倾斜的
        //RR
        if (balanceFactor < -1 && getBalanceFactor(node.right) <= 0){
            return leftRotate(node);
        }

        //LR
        if(balanceFactor > 1 && getBalanceFactor(node.left) < 0){
            node.left = leftRotate(node.left);
            return rightRotate(node);
        }

        //RL
        if(balanceFactor < -1 && getBalanceFactor(node.right) > 0){
            node.right = rightRotate(node.right);
            return leftRotate(node);
        }
        return node;
    }

    // 返回以node为根节点的二分搜索树中，key所在的节点
    private Node getNode(Node node, K key){

        if(node == null)
            return null;

        if(key.equals(node.key))
            return node;
        else if(key.compareTo(node.key) < 0)
            return getNode(node.left, key);
        else // if(key.compareTo(node.key) > 0)
            return getNode(node.right, key);
    }
    public V get(K key){

        Node node = getNode(root, key);
        return node == null ? null : node.value;
    }

    public void set(K key, V newValue){
        Node node = getNode(root, key);
        if(node == null)
            throw new IllegalArgumentException(key + " doesn't exist!");

        node.value = newValue;
    }

    public boolean contains(K e) {
        return contains(root, e);
    }

    private boolean contains(Node node, K key) {
        if (node == null) {
            return false;
        }
        if (key.compareTo(node.key) == 0) {
            return true;
        } else if (key.compareTo(node.key) < 0) {
            return contains(node.left, key);
        } else {
            return contains(node.right, key);
        }
    }

    public void preOrder() {
        preOrder(root);
    }

    private void preOrder(Node node) {
        /*写法一
        if(node == null){
            return;
        }
        System.out.println(node.e);
        preOrder(node.left);
        preOrder(node.right);*/
        if (node != null) {
            System.out.println(node.key);
            preOrder(node.left);
            preOrder(node.right);
        }
    }

    public void preOrderNR() {
        Stack<Node> stack = new Stack<>();
        stack.push(root);
        while (!stack.isEmpty()) {
            Node cur = stack.pop();
            System.out.println(cur.key);
            if (cur.right != null) {
                stack.push(cur.right);
            }
            if (cur.left != null) {
                stack.push(cur.left);
            }
        }
    }

    public void preOrderNR2() {
        Stack<Node> stack = new Stack<>();
        Node cur = root;
        while (cur != null || !stack.isEmpty()) {

            while (cur != null) {
                System.out.println(cur.key);
                stack.push(cur);
                cur = cur.left;
            }
            if (!stack.isEmpty()) {
                cur = stack.pop().right;
            }

        }
    }

    public void inOrder() {
        inOrder(root);
    }

    private void inOrder(Node node) {
        if (node == null) {
            return;
        }
        inOrder(node.left);
        System.out.println(node.key);// 访问该节点
        inOrder(node.right);
    }

    public void postOrder() {
        postOrder(root);
    }

    private void postOrder(Node node) {
        if (node == null) {
            return;
        }
        postOrder(node.left);
        postOrder(node.right);
        System.out.println(node.key);// 访问该节点
    }

    /**
     * 二分搜索树的层序遍历(广度优先遍历)
     */
    public void levelOrder() {
        Queue<Node> queue = new LinkedList<>();
        queue.add(root);
        while (!queue.isEmpty()) {
            Node cur = queue.remove();
            System.out.println(cur.key);

            if (cur.left != null) {
                queue.add(cur.left);
            }
            if (cur.right != null) {
                queue.add(cur.right);
            }
        }
    }

    /**
     * 查找最小元素 使用递归
     *
     * @return
     */
    public K minimum() {
        if (size == 0) {
            throw new IllegalArgumentException("BST is empty");
        }
        return minimum(root).key;
    }

    // 返回以node为根的二分搜索树的最小值所在的节点
    private Node minimum(Node node) {
        if (node.left == null) {
            return node;
        }
        return minimum(node.left);
    }

    /**
     * 查找最大元素 使用递归
     *
     * @return
     */
    public K maximum() {
        if (size == 0) {
            throw new IllegalArgumentException("BST is empty");
        }
        return maximum(root).key;
    }

    private Node maximum(Node node) {
        if (node.right == null) {
            return node;
        }
        return maximum(node.right);
    }

    /**
     * 删除最小节点,并返回最小值
     *
     * @return
     */
    public K removeMin() {
        K ret = minimum();
        root = removeMin(root);
        return ret;
    }

    // 返回删除节点后新的二分搜索树的根
    private Node removeMin(Node node) {
        if (node.left == null) {
            Node rightNode = node.right;
            node.right = null;
            size--;
            return rightNode;
        }

        node.left = removeMin(node.left);
        return node;
    }

    /**
     * 删除最大节点,并返回最大值
     *
     * @return
     */
    public K removeMax() {
        K ret = maximum();
        root = removeMax(root);
        return ret;
    }

    // 返回删除节点后新的二分搜索树的根
    private Node removeMax(Node node) {
        if (node.right == null) {
            Node leftNode = node.left;
            node.left = null;
            size--;
            return leftNode;
        }
        node.right = removeMax(node.right);
        return node;
    }

    /**
     * 从二分搜索树中删除键key的节点
     */
    public V remove(K key){
        Node node = getNode(root, key);
        if(node != null){
            root = remove(root, key);
            return node.value;
        }
        return null;
    }
    //删除以node为根的二分搜索树中指为e的节点 递归算法
    // 返回删除节点后新的二分搜索树的根
    private Node remove(Node node, K key){
        if(node == null){
            return null;
        }
        Node retNode;
        if(key.compareTo(node.key) < 0){
            node.left = remove(node.left, key);
            retNode = node;
        } else if (key.compareTo(node.key) > 0){
            node.right = remove(node.right, key);
            retNode = node;
        } else {// e == node.key
            //待删除的节点左子树为空的情况
            if(node.left == null){
                Node rightNode = node.right;
                node.right = null;
                size--;
                retNode = rightNode;
            } else if(node.right == null){ //待删除的节点右子树为空的情况
                Node leftNode = node.left;
                node.left = null;
                size--;
                retNode = leftNode;
            } else {
                //待删除的节点左右子树都不为空的情况
                //找到比待删除节点大的最小节点,即待删除节点右子树的最小节点
                //用这个节点顶替待删除节点的位置
                Node successor = minimum(node.right);
                successor.right = remove(node.right, successor.key);
                successor.left = node.left;
                //删除
                node.left = node.right = null;
                //返回新的
                retNode = successor;
            }
        }

        if(retNode == null)
            return null;

        //更新高度
        retNode.height = 1 + Math.max(getHeight(retNode.left), getHeight(retNode.right));

        //计算平衡因子
        int balanceFactor = getBalanceFactor(retNode);

        //平衡维护：大于1说明是不平衡，
        // 然后根据其左子树平衡因子大于等于0，
        //整体是左边倾斜的
        // LL
        if (balanceFactor > 1 && getBalanceFactor(retNode.left) >= 0){
            return rightRotate(retNode);
        }

        //平衡维护：小于-1说明是不平衡，
        // 根据其右子树平衡因子小于等于0，
        //整体是右边倾斜的
        //RR
        if (balanceFactor < -1 && getBalanceFactor(retNode.right) <= 0){
            return leftRotate(retNode);
        }

        //LR
        if(balanceFactor > 1 && getBalanceFactor(retNode.left) < 0){
            retNode.left = leftRotate(retNode.left);
            return rightRotate(retNode);
        }

        //RL
        if(balanceFactor < -1 && getBalanceFactor(retNode.right) > 0){
            retNode.right = rightRotate(retNode.right);
            return leftRotate(retNode);
        }

        return retNode;
    }
    //floor

    //ceil

    //rank

    //select
    @Override
    public String toString() {
        StringBuilder res = new StringBuilder();
        generateBSTString(root, 0, res);
        return res.toString();
    }

    private void generateBSTString(Node node, int depth, StringBuilder res) {
        if (node == null) {
            res.append(generateDepthString(depth) + "null\n");
            return;
        }
        res.append(generateDepthString(depth) + node.key + "\n");
        generateBSTString(node.left, depth + 1, res);
        generateBSTString(node.right, depth + 1, res);
    }

    private String generateDepthString(int depth) {
        StringBuilder res = new StringBuilder();
        for (int i = 0; i < depth; i++) {
            res.append("--");
        }
        return res.toString();
    }

    public static void main(String[] args){

        System.out.println("Pride and Prejudice");

        ArrayList<String> words = new ArrayList<>();
        if(FileOperation.readFile("pride-and-prejudice.txt", words)) {
            System.out.println("Total words: " + words.size());

            AVLTree<String, Integer> map = new AVLTree<>();
            for (String word : words) {
                if (map.contains(word))
                    map.set(word, map.get(word) + 1);
                else
                    map.add(word, 1);
            }

            System.out.println("Total different words: " + map.size());
            System.out.println("Frequency of PRIDE: " + map.get("pride"));
            System.out.println("Frequency of PREJUDICE: " + map.get("prejudice"));

            System.out.println("is BST : " + map.isBST());
            System.out.println("is Balanced : " + map.isBalanced());

            for (String word: words){
                map.remove(word);
                if (!map.isBST() || !map.isBalanced()){
                    throw new RuntimeException("Error");
                }
            }
        }

        System.out.println();
    }
}
